Photographic optical system

ABSTRACT

The present invention discloses a photographic optical system which includes a first lens (focal length f1), a second lens (focal length f2), a third lens (focal length f3), a fourth lens (focal length f4), a fifth lens (focal length f5), a sixth lens (focal length f6) and a seventh lens (focal length f7). The photographic optical system disclosed in the present invention by optimizing rationally face shape, distributing focal power, selecting optical material, is designed as a big relative aperture photographic optical system, and can provide the imaging performance in low illumination environment.

FIELD OF THE INVENTION

The present invention discloses a photographic optical system,specifically, a photography optical system of portable electronicdevices.

DESCRIPTION OF RELATED ART

In recent years, with the vigorous development of mini photographiclens, the demand of mini picturing module is rising. The general camerasensor is either photosensitive coupling component or complementarymetal oxide conductive component. With the progress of semiconductormanufacturing technology, the sensor pixel size is smaller. Combinedwith current development trend of electronic product of better function,light, thin, short and small, as a result, the mini camera with goodimaging quality becomes the mainstream of current market.

In the camera sensor lens, the resolution of image gradually increases,pixel size decreases, the lens shall have high resolution and excellentoptical performance, for example, wide angle of lens, imaging in highdynamic range, reducing tolerance sensitivity of the lens, etc. Theexisting camera lens composed of seven pieces of lens, restricted by thestructure, is unable to correct further senior aberration, for examplespherical aberration, so that the imaging performance is limited.

Therefore, it is necessary to provide a kind of new technology solutionto overcome above disadvantage.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiment can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present disclosure. Moreover,in the drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is an exemplary structural diagram of a photographic opticalsystem of the present disclosure.

FIG. 2 is an MTF curve diagram of the photographic optical system shownin FIG. 1.

FIG. 3 is a field curvature curve diagram of the photographic opticalsystem in FIG. 1.

FIG. 4 is a distortion curve diagram of the photographic optical systemin FIG. 1.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The present invention will hereinafter be described in detail withreference to an exemplary embodiment. To make the technical problems tobe solved, technical solutions and beneficial effects of presentdisclosure more apparent, the present disclosure is described in furtherdetail together with the figures and the embodiment. It should beunderstood the specific embodiment described hereby is only to explainthis disclosure, not intended to limit this disclosure.

FIG. 1 is an exemplary structural diagram of a photographic opticalsystem of the present disclosure. The photographic optical system 1comprises seven pieces of lens installed coaxially and lined up from anobject side a to an image side b in turn as follows: a first lens 10, asecond lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, asixth lens 60 and a seventh lens 70. In this embodiment, 7 lenses aboveare plastic lenses.

The first lens 10 is a positive lens and has positive refractive power.An object side surface 11 is concave and is made of plastic material. Anobject side surface 11 or/and the image side surface 13 of the firstlens 10 is spherical or aspherical. In other embodiments, the first lenscan also be a negative lens and can have negative refractive power.

An object side surface 21 of the second lens 20 is convex and an imageside surface 23 is concave and is made of plastic material. Each of theobject side surface 21 and the image side surface 23 of the second lens20 has respectively one inflection point.

An object side 31 of the third lens 30 is convex and an image sidesurface 33 is concave, and is made of plastic material. The object sidesurface 31 and the image side surface 33 of the third lens 30 areaspherical. The image side surface 43 of the third lens 30 has one pointof inflection and one stagnation point.

The object side surface 41 of the fourth lens 40 is convex and the imageside surface 43 of the fourth lens 40 is concave. The fourth lens ismade of plastic material. The object side surface 41 and the image sidesurface 43 of the fourth lens 40 are aspherical. The object side surface41 of the fourth lens 40 has one point of inflection.

An object side surface 51 of the fifth lens 50 is concave and an imageside surface 53 is convex, is made of plastic material. The object sidesurface 51 and the image side surface 53 of the fifth lens 50 areaspherical. The image side surface 53 of the fifth lens 50 has one pointof inflection.

An object side surface 61 of the sixth lens 60 is concave and an imageside surface 63 is convex. The sixth lens 60 is made of plasticmaterial. The object side surface 61 and the image side surface 63 ofthe sixth lens 60 are aspherical. The image side surface 63 of the sixthlens 60 has two points of inflection.

The seventh lens 70 is a negative lens. The object side surface 71 ofthe seventh lens 70 is concave and the image side surface 73 istransferred from concave to convex from optical axis to circumference.The seventh lens 70 is made of plastic. The object side surface 71 andthe image side surface 73 of the seventh lens 70 are aspherical. Theobject side surface 71 of the seventh lens 70 has one point ofinflection. The image side surface 73 of the seventh lens 70 has atleast one point of inflection and one stagnation point. In thisembodiment, the image side surface 73 of the seventh lens 70 has onepoint of inflection and one stagnation point. In other embodiments,other number of inflection point and the stationary point can be set upaccording to the need.

In which, the object side surface is convex, which means the object sidesurface toward the object surface a is at convex shape. The object sidesurface is concave, which means that the object side surface toward theobject surface a is at concave shape. The image side surface is convex,which means that the image side surface toward the image surface b is atconvex shape. The image side surface is concave, which means that theimage side surface toward the image surface b is at concave shape.

The combination refractive power of the first lens 10 and the secondlens 20 is approximate zero refractive power, can correct rationally thespherical aberration, not introduce chromatic aberration and fieldcurvature. The first lens 10 and the second lens 20 meet followingcondition:F12>50 mm or f12<−50 mm, wherein,f12 is the combination focal length of the first lens 10 and the secondlens 20.

The fourth lens 40 and the fifth lens 50 are made of optical materialwith high refractive index and low abbe number, can reduce effectivelychromatic aberration of the system. The seventh lens 70 is a negativerefractive power lens, can reduce effectively the field curvature of thesystem. By optimizing rationally the surface shape of the seven lens,distributing refractive power, selecting optical material, thephotographic optical system 1 has good imaging performance under lowillumination.

The photographic optical system 100 also includes a glass plate 80 and astop 90. The glass plate 80 is located at the side of the image surfaceb of the seventh lens. The glass plate 180 can be a filter to filterlight. Its type can be selected according to actual requirement. Thestop 90 is located at the object side surface 31 of the third lens 30,and can control the amount of light and the depth of field.

In the photographic optical system 100 disclosed in the presentinvention, in order to realize the design requirement ofminiaturization, high sensitivity, high optical performance and wideview angle of the photographic optical system 100, the first lens 10,the second lens 20, the third lens 30, the fourth lens 40, the fifthlens 50, the sixth lens 60 and the seventh lens 70 of the photographicoptical system 1 shall meet following conditions:

1. Focal Length:

Under the overall structure of the photographic optical system 100,focal lengths of the first lens 10, the second lens 20, the third lens30, the fourth lens 40, the fifth lens 50, the sixth lens 60 and theseventh lens 70 of the photographic optical system 100 shall meet thefollowing conditions:30 mm<f1<150 mm;100 mm<f2<500 mm;2 mm<f3<5 mm;−10 mm<f4<−2 mm;−30 mm<f5<−10 mm;1 mm<f6<5 mm;−5 mm<f7<−1.5 mm;10<f1/f<40;20<f2/f<80;0.5<f3/f<1.5;−2.5<f4/f<−0.5;−10<f5/f<−20.2<f6/f<1.2;−1.5<f7/f<−0.4;where,f1: The focal length of the first lens.f2: The focal length of the second lens.f3: The focal length of the third lens.f4: The focal length of the fourth lens.f5: The focal length of the fifth lens.f6: The focal length of the sixth lens.f7: The focal length of the seven lens.f: The focal length of whole photography optical system.

2. Refractive Power

Under the overall structure of the photographic optical system 1, therefractive power of the first lens 10, the second lens 20, the thirdlens 30, the fourth lens 40, the fifth lens 50, the sixth lens 60 andthe seventh lens 70 of the photographic optical system 1 shall meet theconditions:1.50<n1<1.55, 1.50<n2<1.55, 1.50<n3<1.55,1.60<n4<1.70, 1.60<n5<1.70, 1.50<n6<1.55,1.50<n7<1.55;where,n1: The refractive power of the first lens.n2: The refractive power of the second lens.n3: The refractive power of the third lens.n4: The refractive power of the fourth lens.n5: The refractive power of the fifth lens.n6: The refractive power of the sixth lens.n7: The refractive power of the seven lens.

3. Abbe Number

Under the overall structure of the photographic optical system 1, Abbenumber of the first lens 10, the second lens 20, the third lens 30, thefourth lens 40, the fifth lens 50, the sixth lens 60 and the seventhlens 70 of the photographic optical system 1 shall meet the conditions:40<v1<60, 40<v2<60, 40<v3<60, 15<v4<30,15<v5<30, 40<v6<60, 40<v7<60;wherev1: Abbe number of the first lens.v2: Abbe number of the second lens.v3: Abbe number of the third lens.v4: Abbe number of the fourth lens.v5: Abbe number of the fifth lens.v6: Abbe number of the sixth lens.v7: Abbe number of the seven lens.

If the focal length, the refractive power and Abbe number of the firstlens 10, the second lens 20, the third lens 30, the fourth lens 40, thefifth lens 50, the sixth lens 60 and the seventh lens 70 does not meetthe conditions above, the chromatic aberration and telecenriccharacteristics of the photographic optical system 1 may be degraded,and the sensitivity of the photographic optical system 1 will beincreased, it is difficult to realize the miniaturization and wide viewangle of the photographic optical system 1, and is not conducive toreduce cost of the photographic optical system 1.

In this embodiment, the focal length the refractive power and Abbenumber of the first lens 10, the second lens 20, the third lens 30, thefourth lens 40, the fifth lens 50, the sixth lens 60, the seventh lens70 and glass pate 180 of the photographic optical system 1 arerespectively shown in following table:

TABLE 1 Refractive Type Focal length (mm) power Abbe number Photographic3.5 — — optical system The first lens 106.12 1.544 56.1 The second lens237.59 1.544 56.1 The third lens 2.71 1.544 56.1 The fourth lens −5.291.651 21.5 The fifth lens −24.27 1.651 21.5 The sixth lens 2.25 1.54456.1 The seven lens −2.05 1.544 56.1 Glass plate ∞ 1.517 64.2

The continuity of the object side surface and the image side surface,the radius of curvature, SAG and semi-diameter SD of the first lens 10(P1), the second lens 20 (P2), the third lens 30 (P3), the fourth lens40 (P4), the fifth lens 50 (P5), the sixth lens 60 (P6) and the seventhlens 70 (P7) of the photographic optical system 1 are shown in table 2:

TABLE 2 Radius of Semi-diameter Lens Continuity curvature R SAG SD P1Aspherical R11 −4.10 SAG11 −0.389 3.187 Aspherical R12 −3.95 SAG12−0.372 2.947 P2 Aspherical R21 3.24 SAG21 0.203 2.841 Aspherical R223.24 SAG22 0.165 2.593 P3 Aspherical R31 1.46 SAG31 0.275 1.781Aspherical R32 115.75 SAG32 0.003 1.752 P4 Aspherical R41 14.36 SAG410.043 1.722 Aspherical R42 2.78 SAG42 0.154 1.700 P5 Aspherical R51−15.93 SAG51 −0.150 1.691 Aspherical R52 ∞ SAG52 −0.135 1.900 P6Aspherical R61 −5.74 SAG61 −0.134 2.822 Aspherical R62 −1.05 SAG62−0.512 3.230 P7 Aspherical R71 −15.19 SAG71 −0.356 4.017 Aspherical R721.22 SAG72 −0.191 4.711Where,R11: The curvature radius of the object side surface of the first lensP1.R12: The curvature radius of the image side surface of the first lensP1.R21: The curvature radius of the object side surface of the second lensP2.R22: The curvature radius of the image side surface of the second lensP2.R31: The curvature radius of the object side surface of the third lensP3.R32: The curvature radius of the image side surface of the third lensP3.R41: The curvature radius of the object side surface of the fourth lensP4.R42: The curvature radius of the image side surface of the fourth lensP4.R51: The curvature radius of the object side surface of the fifth lensP5.R52: The curvature radius of the image side surface of the fifth lensP5.R61: The curvature radius of the object side surface of the sixth lensP6.R62: The curvature radius of the image side surface of the sixth lensP6.R71: The curvature radius of the object side surface of the seven lensP7.R72: The curvature radius of the image side surface of the seven lensP7.SAG11: the distance from the surface projection point of the first lenson the optical axis to the lens center of the object side surface.SAG12: the distance from the surface projection point of the first lenson the optical axis to the lens center of the image side surface.SAG21: the distance from the surface projection point of the second lenson the optical axis to the lens center of the object side surface.SAG22: the distance from the surface projection point of the second lenson the optical axis to the lens center of the image side surface.SAG31: the distance from the surface projection point of the third lenson the optical axis to the lens center of the object side surface.SAG32: the distance from the surface projection point of the third lenson the optical axis to the lens center of the image side surface.SAG41: the distance from the surface projection point of the fourth lenson the optical axis to the lens center of the object side surface.SAG42: the distance from the surface projection point of the fourth lenson the optical axis to the lens center of the image side surface.SAG51: the distance from the surface projection point of the fifth lenson the optical axis to the lens center of the object side surface.SAG52: the distance from the surface projection point of the fifth lenson the optical axis to the lens center of the image side surface.SAG61: the distance from the surface projection point of the sixth lenson the optical axis to the lens center of the object side surface.SAG62: the distance from the surface projection point of the sixth lenson the optical axis to the lens center of the image side surface.SAG71: the distance from the surface projection point of the seven lenson the optical axis to the lens center of the object side surface.SAG72: the distance from the surface projection point of the seven lenson the optical axis to the lens center of the image side surface.

The thickness of the first lens 10 (P1), the second lens 20 (P2), theaperture 100 (ST), the third lens 30 (P3), the fourth lens 40 (P4), thefifth lens 50 (P5), the sixth lens 60 (P6), the seventh lens 70 (P7) andthe glass plate 180 (Tg) of the photographic optical system 1 is shownin table 3:

TABLE 3 Thickness (mm) T1 0.367 T12 0.050 T2 0.250 ST 0.421 T23 −0.245T3 0.604 T34 0.050 T4 0.250 T45 0.391 T5 0.250 T56 0.361 T6 0.660 T670.293 T7 0.442 Tg 0.225Where,T1: The thickness of the first lens.T12: The axial distance from the image side surface of the first lensand the object side surface of the second lens.T2: The thickness of the second lens.ST: The thickness of the aperture.T23: The axial distance from the aperture to the object side surface ofthe third lens.T3: The thickness of the third lens.T34: The axial distance from the image side surface of the third lensand the object side surface of the fourth lens.T4: The thickness of the fourth lens.T45: The axial distance from the image side surface of the fourth lensto the fifth lens.T5: The thickness of the fifth lens.T56: The axial distance from the fifth lens to the sixth lens.T6: The thickness of the sixth lens.T67: The axial distance from the sixth lens to the seventh lens.T7: The thickness of the seventh lens.

TABLE 4 Relation table between main light angle CRA and the image heightof the photographic optical system Biggest image height percentage Imageheight (mm) CRA (degree) 0.1H 0.294 5.4 0.2H 0.588 10.7 0.3H 0.882 15.90.4H 1.176 21.0 0.5H 1.470 25.6 0.6H 1.764 29.2 0.7H 2.058 31.2 0.8H2.352 31.2 0.9H 2.646 29.7 1.0H 2.94 26.9 max — 31.5

In this embodiment, DFOV=78.00°, HFOV=62.40°, VFOV=46.80°, in which: FOVis defined as the biggest view angle range of the photographic opticalsystem, HFOV is defined as horizontal view angle, DFOV is defined asdiagonal view angle, VFOV is defined as vertical view angle.

Please refer also to FIGS. 2-4, the photographic optical system 1disclosed in the present invention has high optical performance.

In addition, in the photographic optical system 1 disclosed in thepresent invention, the photographic optical system 1 is designed on thebasis of the optical system with large relative aperture, total opticallength is less than 5.2 mm, view angle is between 78° to 88°. The ratiobetween the focal length and the system overall optical length of thephotographic optical system meets the expression f/TTL>0.65.

The photographic optical system 1 disclosed in the present invention hasfollowing beneficial advantages:

In present invention, through optimizing surface type, distributingfocal power, selecting optical material, a big relative aperturephotographic optical system is designed, which can provide good imagingperformance in low illumination environment. The image is clear. Thecombination focal power of the first lens 10 and the second lens 20 isapproximate zero focal power lens, can correct rationally the sphericalaberration, but does not introduce chromatic aberration and fieldcurvature. The fourth lens 40 and the fifth lens 50 are made of materialwith high refractive index and low abbe number, can reduce effectivelychromatic aberration of the system. The seventh lens 70 is negativerefractive power lens which can reduce effectively the field curvatureof the system.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present exemplary embodiment havebeen set forth in the foregoing description, together with details ofthe structures and functions of the embodiment, the disclosure isillustrative only, and changes may be made in detail, especially inmatters of shape, size, and arrangement of parts within the principlesof the invention to the full extent indicated by the broad generalmeaning of the terms where the appended claims are expressed.

What is claimed is:
 1. A photographic optical system comprising, in anorder from an object side to an image side: a first lens, a second lens,a third lens, a fourth lens, a fifth lens, a sixth lens and a seventhlens; wherein the photographic optical system further meets thefollowing conditions (1)˜(7):10<f1/f<40  (1);20<f2/f<80  (2);0.5<f3/f<1.5  (3);−2.5<f4/f<−0.5  (4);−10<f5/f<−2  (5);0.2<f6/f<1.2  (6);−1.5<f7/f<−0.4  (7); where, f1: The focal length of the first lens; f2:The focal length of the second lens; f3: The focal length of the thirdlens; f4: The focal length of the fourth lens; f5: The focal length ofthe fifth lens; f6: The focal length of the sixth lens; f7: The focallength of the seven lens; f: The focal length of whole photographyoptical system.
 2. The photographic optical system as described in claim1 further meeting the following conditions (1a)-(7a):30 mm<f1<150 mm  (1a);100 mm<f2<500 mm  (2a);2 mm<f3<5 mm  (3a);−10 mm<f4<−2 mm  (4a);−30 mm<f5<−10 mm  (5a);1mm<f6<5 mm  (6a);−5 mm<f7<−1.5 mm  (7a).
 3. The photographic optical system as describedin claim 1 further meeting the following conditions (1b)-(7b):1.50<n1<1.55  (1b);1.50<n2<1.55  (2b);1.50<n3<1.55  (3b);1.60<n4<1.70  (4b);1.60<n5<1.70  (5b);1.50<n6<1.55  (6b);1.50<n7<1.55  (7b); where, n1: The refractive power of the first lens;n2: The refractive power of the second lens; n3: The refractive power ofthe third lens; n4: The refractive power of the fourth lens; n5: Therefractive power of the fifth lens; n6: The refractive power of thesixth lens; n7: The refractive power of the seven lens.
 4. Thephotography optical system as described in claim 1 further meeting thefollowing conditions (1c)-(7c):40<v1<60  (1c);40<v2<60  (2c);40<v3<60  (3c);15<v4<30  (4c);15<v5<30  (5c);40<v6<60  (6c);40<v7<60  (7c); where, v1: Abbe number of the first lens; v2: Abbenumber of the second lens; v3: Abbe number of the third lens; v4: Abbenumber of the fourth lens; v5: Abbe number of the fifth lens; v6: Abbenumber of the sixth lens; v7: Abbe number of the seven lens.
 5. Thephotography optical system as described in claim 1, wherein the firstlens and the second lens meet following condition:f12>50 mm or f12<−50 mm. where, f12: The combination focal length of thefirst lens and the second lens.
 6. The photography optical system asdescribed in claim 2, wherein the first lens is a positive lens or anegative lens and the object side surface of the first lens is concave.7. The photography optical system as described in claim 2, wherein theseventh lens is a negative lens.
 8. The photography optical system asdescribed in claim 1 further meeting the following conditions:TTL<5.2 mm;78°<FOV<88°; where, TTL: The distance from the object side surface tothe imaging surface of the first lens; FOV: The biggest view angle rangeof the photographical optical system.
 9. The photography optical systemas described in claim 1, wherein the ratio between the system opticaloverall length and focal length of the photographic optical system meetsthe following condition:f/TTL>0.65 where, TTL: The distance from the object side surface to theimaging surface of the first lens.
 10. The photography optical system asdescribed in claim 7, wherein the image side surface of the seventh lenshas at least one point of inflection and one stagnation point.